En avoir plein son casque — a French expression from Québec meaning “to be fed up.”
J’en ai plein mon casque.
I’m fed up. I’m sick of it. I’ve had it.
You may hear casque pronounced as cass in this expression.
A search on Google reveals what people are sick of.
Someone’s sick of getting tickets:
J’en ai plein mon casque d’avoir des contraventions. (source)
Someone else is sick of the winter:
J’en ai plein mon casque de l’hiver! (source)
This mother’s fed up with her children’s messy room:
J’en ai plein mon casque de voir la chambre dans cet état! (source)
Another mother is sick of changing her child’s diaper:
J’en ai plein mon casque de changer sa couche. (source)
And this mother hasn’t even got to the diapers yet:
J’en ai plein mon casque d’être enceinte. (source)
